Mark Inch, the director of the federal Bureau of Prisons, resigned on Friday after less than a year at the agency, which has faced congressional scrutiny over allegations of staffing shortages and other issues.

It was not immediately clear why Mr. Inch, a retired Army major general who had joined the bureau in September, resigned. Hugh Hurwitz, the bureau’s assistant director, will step in as acting director. Mr. Hurwitz started his career in the prison system as a law clerk in the bureau’s office of the general counsel in 1988.

“I would also like to thank Mark Inch for proudly serving the Department of Justice as the director of the Federal Bureau of Prisons and wish him luck in his future endeavors,” Attorney General Jeff Sessions said in a statement.

The announcement came on the same day that the White House was engaged in a summit meeting on prison reform. At the meeting, President Trump, who did not mention Mr. Inch’s resignation, said: “We want the finest — the finest prison reform that you can have anywhere. The finest.”

The bureau, a unit of the Justice Department, administers the federal prison system, which includes more than 120 facilities and more than 180,000 inmates.

Over the last year, the prison agency has been the subject of a review by the House Oversight and Government Reform Committee over allegations of staffing shortages, sexual harassment and other problems. It was unclear whether the committee’s examination was connected to Mr. Inch’s resignation.

Last week, reports emerged that the Justice Department was seeking to roll back policies offering protections for gay and transgender people at the prisons bureau. The agency will now use an inmate’s biological sex to initially determine where that person will be housed and which bathroom that person will use.

A version of this article appears in print on , on Page A14 of the New York edition with the headline: Director Steps Down At Bureau Of Prisons. Order Reprints | Today’s Paper | Subscribe